Move Codec2-related code from hardware/google/av

Test: None
Bug: 112362730
Change-Id: Ie2f8ff431d65c40333f267ab9877d47089adeea4
diff --git a/media/codec2/include/C2Param.h b/media/codec2/include/C2Param.h
new file mode 100644
index 0000000..40be3b3
--- /dev/null
+++ b/media/codec2/include/C2Param.h
@@ -0,0 +1,1673 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef C2PARAM_H_
+#define C2PARAM_H_
+
+#include <C2.h>
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <algorithm>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+/// \addtogroup Parameters
+/// @{
+
+/// \defgroup internal Internal helpers.
+
+/*!
+ * \file
+ * PARAMETERS: SETTINGs, TUNINGs, and INFOs
+ * ===
+ *
+ * These represent miscellaneous control and metadata information and are likely copied into
+ * kernel space. Therefore, these are C-like structures designed to carry just a small amount of
+ * information. We are using C++ to be able to add constructors, as well as non-virtual and class
+ * methods.
+ *
+ * ==Specification details:
+ *
+ * Restrictions:
+ *   - must be POD struct, e.g. no vtable (no virtual destructor)
+ *   - must have the same size in 64-bit and 32-bit mode (no size_t)
+ *   - as such, no pointer members
+ *   - some common member field names are reserved as they are defined as methods for all
+ *     parameters:
+ *     they are: size, type, kind, index and stream
+ *
+ * Behavior:
+ * - Params can be global (not related to input or output), related to input or output,
+ *   or related to an input/output stream.
+ * - All params are queried/set using a unique param index, which incorporates a potential stream
+ *   index and/or port.
+ * - Querying (supported) params MUST never fail.
+ * - All params MUST have default values.
+ * - If some fields have "unsupported" or "invalid" values during setting, this SHOULD be
+ *   communicated to the app.
+ *   a) Ideally, this should be avoided.  When setting parameters, in general, component should do
+ *     "best effort" to apply all settings. It should change "invalid/unsupported" values to the
+ *     nearest supported values.
+ *   - This is communicated to the client by changing the source values in tune()/
+ *     configure().
+ *   b) If falling back to a supported value is absolutely impossible, the component SHALL return
+ *     an error for the specific setting, but should continue to apply other settings.
+ *     TODO: this currently may result in unintended results.
+ *
+ * **NOTE:** unlike OMX, params are not versioned. Instead, a new struct with new param index
+ * SHALL be added as new versions are required.
+ *
+ * The proper subtype (Setting, Info or Param) is incorporated into the class type. Define structs
+ * to define multiple subtyped versions of related parameters.
+ *
+ * ==Implementation details:
+ *
+ * - Use macros to define parameters
+ * - All parameters must have a default constructor
+ *   - This is only used for instantiating the class in source (e.g. will not be used
+ *     when building a parameter by the framework from key/value pairs.)
+ */
+
+/// \ingroup internal
+
+/**
+ * Parameter base class.
+ */
+struct C2Param {
+    // param index encompasses the following:
+    //
+    // - kind (setting, tuning, info, struct)
+    // - scope
+    //   - direction (global, input, output)
+    //   - stream flag
+    //   - stream ID (usually 0)
+    // - and the parameter's type (core index)
+    //   - flexible parameter flag
+    //   - vendor extension flag
+    //   - type index (this includes the vendor extension flag)
+    //
+    // layout:
+    //
+    //        kind : <------- scope -------> : <----- core index ----->
+    //      +------+-----+---+------+--------+----|------+--------------+
+    //      | kind | dir | - |stream|streamID|flex|vendor|  type index  |
+    //      +------+-----+---+------+--------+----+------+--------------+
+    //  bit: 31..30 29.28       25   24 .. 17  16    15   14    ..     0
+    //
+public:
+    /**
+     * C2Param kinds, usable as bitmaps.
+     */
+    enum kind_t : uint32_t {
+        NONE    = 0,
+        STRUCT  = (1 << 0),
+        INFO    = (1 << 1),
+        SETTING = (1 << 2),
+        TUNING  = (1 << 3) | SETTING, // tunings are settings
+    };
+
+    /**
+     * The parameter type index specifies the underlying parameter type of a parameter as
+     * an integer value.
+     *
+     * Parameter types are divided into two groups: platform types and vendor types.
+     *
+     * Platform types are defined by the platform and are common for all implementations.
+     *
+     * Vendor types are defined by each vendors, so they may differ between implementations.
+     * It is recommended that vendor types be the same for all implementations by a specific
+     * vendor.
+     */
+    typedef uint32_t type_index_t;
+    enum : uint32_t {
+            TYPE_INDEX_VENDOR_START = 0x00008000, ///< vendor indices SHALL start after this
+    };
+
+    /**
+     * Core index is the underlying parameter type for a parameter. It is used to describe the
+     * layout of the parameter structure regardless of the component or parameter kind/scope.
+     *
+     * It is used to identify and distinguish global parameters, and also parameters on a given
+     * port or stream. They must be unique for the set of global parameters, as well as for the
+     * set of parameters on each port or each stream, but the same core index can be used for
+     * parameters on different streams or ports, as well as for global parameters and port/stream
+     * parameters.
+     *
+     * Multiple parameter types can share the same layout.
+     *
+     * \note The layout for all parameters with the same core index across all components must
+     * be identical.
+     */
+    struct CoreIndex {
+    //public:
+        enum : uint32_t {
+            IS_FLEX_FLAG = 0x00010000,
+        };
+
+    protected:
+        enum : uint32_t {
+            KIND_MASK      = 0xC0000000,
+            KIND_STRUCT    = 0x00000000,
+            KIND_TUNING    = 0x40000000,
+            KIND_SETTING   = 0x80000000,
+            KIND_INFO      = 0xC0000000,
+
+            DIR_MASK       = 0x30000000,
+            DIR_GLOBAL     = 0x20000000,
+            DIR_UNDEFINED  = DIR_MASK, // MUST have all bits set
+            DIR_INPUT      = 0x00000000,
+            DIR_OUTPUT     = 0x10000000,
+
+            IS_STREAM_FLAG  = 0x02000000,
+            STREAM_ID_MASK  = 0x01FE0000,
+            STREAM_ID_SHIFT = 17,
+            MAX_STREAM_ID   = STREAM_ID_MASK >> STREAM_ID_SHIFT,
+            STREAM_MASK     = IS_STREAM_FLAG | STREAM_ID_MASK,
+
+            IS_VENDOR_FLAG  = 0x00008000,
+            TYPE_INDEX_MASK = 0x0000FFFF,
+            CORE_MASK       = TYPE_INDEX_MASK | IS_FLEX_FLAG,
+        };
+
+    public:
+        /// constructor/conversion from uint32_t
+        inline CoreIndex(uint32_t index) : mIndex(index) { }
+
+        // no conversion from uint64_t
+        inline CoreIndex(uint64_t index) = delete;
+
+        /// returns true iff this is a vendor extension parameter
+        inline bool isVendor() const { return mIndex & IS_VENDOR_FLAG; }
+
+        /// returns true iff this is a flexible parameter (with variable size)
+        inline bool isFlexible() const { return mIndex & IS_FLEX_FLAG; }
+
+        /// returns the core index
+        /// This is the combination of the parameter type index and the flexible flag.
+        inline uint32_t coreIndex() const { return mIndex & CORE_MASK; }
+
+        /// returns the parameter type index
+        inline type_index_t typeIndex() const { return mIndex & TYPE_INDEX_MASK; }
+
+        DEFINE_FIELD_AND_MASK_BASED_COMPARISON_OPERATORS(CoreIndex, mIndex, CORE_MASK)
+
+    protected:
+        uint32_t mIndex;
+    };
+
+    /**
+     * Type encompasses the parameter's kind (tuning, setting, info), its scope (whether the
+     * parameter is global, input or output, and whether it is for a stream) and the its base
+     * index (which also determines its layout).
+     */
+    struct Type : public CoreIndex {
+    //public:
+        /// returns true iff this is a global parameter (not for input nor output)
+        inline bool isGlobal() const { return (mIndex & DIR_MASK) == DIR_GLOBAL; }
+        /// returns true iff this is an input or input stream parameter
+        inline bool forInput() const { return (mIndex & DIR_MASK) == DIR_INPUT; }
+        /// returns true iff this is an output or output stream parameter
+        inline bool forOutput() const { return (mIndex & DIR_MASK) == DIR_OUTPUT; }
+
+        /// returns true iff this is a stream parameter
+        inline bool forStream() const { return mIndex & IS_STREAM_FLAG; }
+        /// returns true iff this is a port (input or output) parameter
+        inline bool forPort() const   { return !forStream() && !isGlobal(); }
+
+        /// returns the parameter type: the parameter index without the stream ID
+        inline uint32_t type() const { return mIndex & (~STREAM_ID_MASK); }
+
+        /// return the kind (struct, info, setting or tuning) of this param
+        inline kind_t kind() const {
+            switch (mIndex & KIND_MASK) {
+                case KIND_STRUCT: return STRUCT;
+                case KIND_INFO: return INFO;
+                case KIND_SETTING: return SETTING;
+                case KIND_TUNING: return TUNING;
+                default: return NONE; // should not happen
+            }
+        }
+
+        /// constructor/conversion from uint32_t
+        inline Type(uint32_t index) : CoreIndex(index) { }
+
+        // no conversion from uint64_t
+        inline Type(uint64_t index) = delete;
+
+        DEFINE_FIELD_AND_MASK_BASED_COMPARISON_OPERATORS(Type, mIndex, ~STREAM_ID_MASK)
+
+    private:
+        friend struct C2Param;   // for setPort()
+        friend struct C2Tuning;  // for KIND_TUNING
+        friend struct C2Setting; // for KIND_SETTING
+        friend struct C2Info;    // for KIND_INFO
+        // for DIR_GLOBAL
+        template<typename T, typename S, int I, class F> friend struct C2GlobalParam;
+        template<typename T, typename S, int I, class F> friend struct C2PortParam;   // for kDir*
+        template<typename T, typename S, int I, class F> friend struct C2StreamParam; // for kDir*
+        friend struct _C2ParamInspector; // for testing
+
+        /**
+         * Sets the port/stream direction.
+         * @return true on success, false if could not set direction (e.g. it is global param).
+         */
+        inline bool setPort(bool output) {
+            if (isGlobal()) {
+                return false;
+            } else {
+                mIndex = (mIndex & ~DIR_MASK) | (output ? DIR_OUTPUT : DIR_INPUT);
+                return true;
+            }
+        }
+    };
+
+    /**
+     * index encompasses all remaining information: basically the stream ID.
+     */
+    struct Index : public Type {
+        /// returns the index as uint32_t
+        inline operator uint32_t() const { return mIndex; }
+
+        /// constructor/conversion from uint32_t
+        inline Index(uint32_t index) : Type(index) { }
+
+        /// copy constructor
+        inline Index(const Index &index) = default;
+
+        // no conversion from uint64_t
+        inline Index(uint64_t index) = delete;
+
+        /// returns the stream ID or ~0 if not a stream
+        inline unsigned stream() const {
+            return forStream() ? rawStream() : ~0U;
+        }
+
+        /// Returns an index with stream field set to given stream.
+        inline Index withStream(unsigned stream) const {
+            Index ix = mIndex;
+            (void)ix.setStream(stream);
+            return ix;
+        }
+
+        /// sets the port (direction). Returns true iff successful.
+        inline Index withPort(bool output) const {
+            Index ix = mIndex;
+            (void)ix.setPort(output);
+            return ix;
+        }
+
+        DEFINE_FIELD_BASED_COMPARISON_OPERATORS(Index, mIndex)
+
+    private:
+        friend struct C2Param;           // for setStream, MakeStreamId, isValid
+        friend struct _C2ParamInspector; // for testing
+
+        /**
+         * @return true if the type is valid, e.g. direction is not undefined AND
+         * stream is 0 if not a stream param.
+         */
+        inline bool isValid() const {
+            // there is no Type::isValid (even though some of this check could be
+            // performed on types) as this is only used on index...
+            return (forStream() ? rawStream() < MAX_STREAM_ID : rawStream() == 0)
+                    && (mIndex & DIR_MASK) != DIR_UNDEFINED;
+        }
+
+        /// returns the raw stream ID field
+        inline unsigned rawStream() const {
+            return (mIndex & STREAM_ID_MASK) >> STREAM_ID_SHIFT;
+        }
+
+        /// returns the streamId bitfield for a given |stream|. If stream is invalid,
+        /// returns an invalid bitfield.
+        inline static uint32_t MakeStreamId(unsigned stream) {
+            // saturate stream ID (max value is invalid)
+            if (stream > MAX_STREAM_ID) {
+                stream = MAX_STREAM_ID;
+            }
+            return (stream << STREAM_ID_SHIFT) & STREAM_ID_MASK;
+        }
+
+        inline bool convertToStream(bool output, unsigned stream) {
+            mIndex = (mIndex & ~DIR_MASK) | IS_STREAM_FLAG;
+            (void)setPort(output);
+            return setStream(stream);
+        }
+
+        inline void convertToPort(bool output) {
+            mIndex = (mIndex & ~(DIR_MASK | IS_STREAM_FLAG));
+            (void)setPort(output);
+        }
+
+        inline void convertToGlobal() {
+            mIndex = (mIndex & ~(DIR_MASK | IS_STREAM_FLAG)) | DIR_GLOBAL;
+        }
+
+        /**
+         * Sets the stream index.
+         * \return true on success, false if could not set index (e.g. not a stream param).
+         */
+        inline bool setStream(unsigned stream) {
+            if (forStream()) {
+                mIndex = (mIndex & ~STREAM_ID_MASK) | MakeStreamId(stream);
+                return this->stream() < MAX_STREAM_ID;
+            }
+            return false;
+        }
+    };
+
+public:
+    // public getters for Index methods
+
+    /// returns true iff this is a vendor extension parameter
+    inline bool isVendor() const { return _mIndex.isVendor(); }
+    /// returns true iff this is a flexible parameter
+    inline bool isFlexible() const { return _mIndex.isFlexible(); }
+    /// returns true iff this is a global parameter (not for input nor output)
+    inline bool isGlobal() const { return _mIndex.isGlobal(); }
+    /// returns true iff this is an input or input stream parameter
+    inline bool forInput() const { return _mIndex.forInput(); }
+    /// returns true iff this is an output or output stream parameter
+    inline bool forOutput() const { return _mIndex.forOutput(); }
+
+    /// returns true iff this is a stream parameter
+    inline bool forStream() const { return _mIndex.forStream(); }
+    /// returns true iff this is a port (input or output) parameter
+    inline bool forPort() const   { return _mIndex.forPort(); }
+
+    /// returns the stream ID or ~0 if not a stream
+    inline unsigned stream() const { return _mIndex.stream(); }
+
+    /// returns the parameter type: the parameter index without the stream ID
+    inline Type type() const { return _mIndex.type(); }
+
+    /// returns the index of this parameter
+    /// \todo: should we restrict this to C2ParamField?
+    inline uint32_t index() const { return (uint32_t)_mIndex; }
+
+    /// returns the core index of this parameter
+    inline CoreIndex coreIndex() const { return _mIndex.coreIndex(); }
+
+    /// returns the kind of this parameter
+    inline kind_t kind() const { return _mIndex.kind(); }
+
+    /// returns the size of the parameter or 0 if the parameter is invalid
+    inline size_t size() const { return _mSize; }
+
+    /// returns true iff the parameter is valid
+    inline operator bool() const { return _mIndex.isValid() && _mSize > 0; }
+
+    /// returns true iff the parameter is invalid
+    inline bool operator!() const { return !operator bool(); }
+
+    // equality is done by memcmp (use equals() to prevent any overread)
+    inline bool operator==(const C2Param &o) const {
+        return equals(o) && memcmp(this, &o, _mSize) == 0;
+    }
+    inline bool operator!=(const C2Param &o) const { return !operator==(o); }
+
+    /// safe(r) type cast from pointer and size
+    inline static C2Param* From(void *addr, size_t len) {
+        // _mSize must fit into size, but really C2Param must also to be a valid param
+        if (len < sizeof(C2Param)) {
+            return nullptr;
+        }
+        // _mSize must match length
+        C2Param *param = (C2Param*)addr;
+        if (param->_mSize != len) {
+            return nullptr;
+        }
+        return param;
+    }
+
+    /// Returns managed clone of |orig| at heap.
+    inline static std::unique_ptr<C2Param> Copy(const C2Param &orig) {
+        if (orig.size() == 0) {
+            return nullptr;
+        }
+        void *mem = ::operator new (orig.size());
+        C2Param *param = new (mem) C2Param(orig.size(), orig._mIndex);
+        param->updateFrom(orig);
+        return std::unique_ptr<C2Param>(param);
+    }
+
+    /// Returns managed clone of |orig| as a stream parameter at heap.
+    inline static std::unique_ptr<C2Param> CopyAsStream(
+            const C2Param &orig, bool output, unsigned stream) {
+        std::unique_ptr<C2Param> copy = Copy(orig);
+        if (copy) {
+            copy->_mIndex.convertToStream(output, stream);
+        }
+        return copy;
+    }
+
+    /// Returns managed clone of |orig| as a port parameter at heap.
+    inline static std::unique_ptr<C2Param> CopyAsPort(const C2Param &orig, bool output) {
+        std::unique_ptr<C2Param> copy = Copy(orig);
+        if (copy) {
+            copy->_mIndex.convertToPort(output);
+        }
+        return copy;
+    }
+
+    /// Returns managed clone of |orig| as a global parameter at heap.
+    inline static std::unique_ptr<C2Param> CopyAsGlobal(const C2Param &orig) {
+        std::unique_ptr<C2Param> copy = Copy(orig);
+        if (copy) {
+            copy->_mIndex.convertToGlobal();
+        }
+        return copy;
+    }
+
+#if 0
+    template<typename P, class=decltype(C2Param(P()))>
+    P *As() { return P::From(this); }
+    template<typename P>
+    const P *As() const { return const_cast<const P*>(P::From(const_cast<C2Param*>(this))); }
+#endif
+
+protected:
+    /// sets the stream field. Returns true iff successful.
+    inline bool setStream(unsigned stream) {
+        return _mIndex.setStream(stream);
+    }
+
+    /// sets the port (direction). Returns true iff successful.
+    inline bool setPort(bool output) {
+        return _mIndex.setPort(output);
+    }
+
+public:
+    /// invalidate this parameter. There is no recovery from this call; e.g. parameter
+    /// cannot be 'corrected' to be valid.
+    inline void invalidate() { _mSize = 0; }
+
+    // if other is the same kind of (valid) param as this, copy it into this and return true.
+    // otherwise, do not copy anything, and return false.
+    inline bool updateFrom(const C2Param &other) {
+        if (other._mSize <= _mSize && other._mIndex == _mIndex && _mSize > 0) {
+            memcpy(this, &other, other._mSize);
+            return true;
+        }
+        return false;
+    }
+
+protected:
+    // returns |o| if it is a null ptr, or if can suitably be a param of given |type| (e.g. has
+    // same type (ignoring stream ID), and size). Otherwise, returns null. If |checkDir| is false,
+    // allow undefined or different direction (e.g. as constructed from C2PortParam() vs.
+    // C2PortParam::input), but still require equivalent type (stream, port or global); otherwise,
+    // return null.
+    inline static const C2Param* IfSuitable(
+            const C2Param* o, size_t size, Type type, size_t flexSize = 0, bool checkDir = true) {
+        if (o == nullptr || o->_mSize < size || (flexSize && ((o->_mSize - size) % flexSize))) {
+            return nullptr;
+        } else if (checkDir) {
+            return o->_mIndex.type() == type.mIndex ? o : nullptr;
+        } else if (o->_mIndex.isGlobal()) {
+            return nullptr;
+        } else {
+            return ((o->_mIndex.type() ^ type.mIndex) & ~Type::DIR_MASK) ? nullptr : o;
+        }
+    }
+
+    /// base constructor
+    inline C2Param(uint32_t paramSize, Index paramIndex)
+        : _mSize(paramSize),
+          _mIndex(paramIndex) {
+        if (paramSize > sizeof(C2Param)) {
+            memset(this + 1, 0, paramSize - sizeof(C2Param));
+        }
+    }
+
+    /// base constructor with stream set
+    inline C2Param(uint32_t paramSize, Index paramIndex, unsigned stream)
+        : _mSize(paramSize),
+          _mIndex(paramIndex | Index::MakeStreamId(stream)) {
+        if (paramSize > sizeof(C2Param)) {
+            memset(this + 1, 0, paramSize - sizeof(C2Param));
+        }
+        if (!forStream()) {
+            invalidate();
+        }
+    }
+
+private:
+    friend struct _C2ParamInspector; // for testing
+
+    /// returns true iff |o| has the same size and index as this. This performs the
+    /// basic check for equality.
+    inline bool equals(const C2Param &o) const {
+        return _mSize == o._mSize && _mIndex == o._mIndex;
+    }
+
+    uint32_t _mSize;
+    Index _mIndex;
+};
+
+/// \ingroup internal
+/// allow C2Params access to private methods, e.g. constructors
+#define C2PARAM_MAKE_FRIENDS \
+    template<typename U, typename S, int I, class F> friend struct C2GlobalParam; \
+    template<typename U, typename S, int I, class F> friend struct C2PortParam; \
+    template<typename U, typename S, int I, class F> friend struct C2StreamParam; \
+
+/**
+ * Setting base structure for component method signatures. Wrap constructors.
+ */
+struct C2Setting : public C2Param {
+protected:
+    template<typename ...Args>
+    inline C2Setting(const Args(&... args)) : C2Param(args...) { }
+public: // TODO
+    enum : uint32_t { PARAM_KIND = Type::KIND_SETTING };
+};
+
+/**
+ * Tuning base structure for component method signatures. Wrap constructors.
+ */
+struct C2Tuning : public C2Setting {
+protected:
+    template<typename ...Args>
+    inline C2Tuning(const Args(&... args)) : C2Setting(args...) { }
+public: // TODO
+    enum : uint32_t { PARAM_KIND = Type::KIND_TUNING };
+};
+
+/**
+ * Info base structure for component method signatures. Wrap constructors.
+ */
+struct C2Info : public C2Param {
+protected:
+    template<typename ...Args>
+    inline C2Info(const Args(&... args)) : C2Param(args...) { }
+public: // TODO
+    enum : uint32_t { PARAM_KIND = Type::KIND_INFO };
+};
+
+/**
+ * Structure uniquely specifying a field in an arbitrary structure.
+ *
+ * \note This structure is used differently in C2FieldDescriptor to
+ * identify array fields, such that _mSize is the size of each element. This is
+ * because the field descriptor contains the array-length, and we want to keep
+ * a relevant element size for variable length arrays.
+ */
+struct _C2FieldId {
+//public:
+    /**
+     * Constructor used for C2FieldDescriptor that removes the array extent.
+     *
+     * \param[in] offset pointer to the field in an object at address 0.
+     */
+    template<typename T, class B=typename std::remove_extent<T>::type>
+    inline _C2FieldId(T* offset)
+        : // offset is from "0" so will fit on 32-bits
+          _mOffset((uint32_t)(uintptr_t)(offset)),
+          _mSize(sizeof(B)) { }
+
+    /**
+     * Direct constructor from offset and size.
+     *
+     * \param[in] offset offset of the field.
+     * \param[in] size size of the field.
+     */
+    inline _C2FieldId(size_t offset, size_t size)
+        : _mOffset(offset), _mSize(size) {}
+
+    /**
+     * Constructor used to identify a field in an object.
+     *
+     * \param U[type] pointer to the object that contains this field. This is needed in case the
+     *        field is in an (inherited) base class, in which case T will be that base class.
+     * \param pm[im] member pointer to the field
+     */
+    template<typename R, typename T, typename U, typename B=typename std::remove_extent<R>::type>
+    inline _C2FieldId(U *, R T::* pm)
+        : _mOffset((uint32_t)(uintptr_t)(&(((U*)256)->*pm)) - 256u),
+          _mSize(sizeof(B)) { }
+
+    /**
+     * Constructor used to identify a field in an object.
+     *
+     * \param pm[im] member pointer to the field
+     */
+    template<typename R, typename T, typename B=typename std::remove_extent<R>::type>
+    inline _C2FieldId(R T::* pm)
+        : _mOffset((uint32_t)(uintptr_t)(&(((T*)0)->*pm))),
+          _mSize(sizeof(B)) { }
+
+    inline bool operator==(const _C2FieldId &other) const {
+        return _mOffset == other._mOffset && _mSize == other._mSize;
+    }
+
+    inline bool operator<(const _C2FieldId &other) const {
+        return _mOffset < other._mOffset ||
+            // NOTE: order parent structure before sub field
+            (_mOffset == other._mOffset && _mSize > other._mSize);
+    }
+
+    DEFINE_OTHER_COMPARISON_OPERATORS(_C2FieldId)
+
+#if 0
+    inline uint32_t offset() const { return _mOffset; }
+    inline uint32_t size() const { return _mSize; }
+#endif
+
+#if defined(FRIEND_TEST)
+    friend void PrintTo(const _C2FieldId &d, ::std::ostream*);
+#endif
+
+private:
+    friend struct _C2ParamInspector;
+    friend struct C2FieldDescriptor;
+
+    uint32_t _mOffset; // offset of field
+    uint32_t _mSize;   // size of field
+};
+
+/**
+ * Structure uniquely specifying a 'field' in a configuration. The field
+ * can be a field of a configuration, a subfield of a field of a configuration,
+ * and even the whole configuration. Moreover, if the field can point to an
+ * element in a array field, or to the entire array field.
+ *
+ * This structure is used for querying supported values for a field, as well
+ * as communicating configuration failures and conflicts when trying to change
+ * a configuration for a component/interface or a store.
+ */
+struct C2ParamField {
+//public:
+    /**
+     * Create a field identifier using a configuration parameter (variable),
+     * and a pointer to member.
+     *
+     * ~~~~~~~~~~~~~ (.cpp)
+     *
+     * struct C2SomeParam {
+     *   uint32_t mField;
+     *   uint32_t mArray[2];
+     *   C2OtherStruct mStruct;
+     *   uint32_t mFlexArray[];
+     * } *mParam;
+     *
+     * C2ParamField(mParam, &mParam->mField);
+     * C2ParamField(mParam, &mParam->mArray);
+     * C2ParamField(mParam, &mParam->mArray[0]);
+     * C2ParamField(mParam, &mParam->mStruct.mSubField);
+     * C2ParamField(mParam, &mParam->mFlexArray);
+     * C2ParamField(mParam, &mParam->mFlexArray[2]);
+     *
+     * ~~~~~~~~~~~~~
+     *
+     * \todo fix what this is for T[] (for now size becomes T[1])
+     *
+     * \note this does not work for 64-bit members as it triggers a
+     * 'taking address of packed member' warning.
+     *
+     * \param param pointer to parameter
+     * \param offset member pointer
+     */
+    template<typename S, typename T>
+    inline C2ParamField(S* param, T* offset)
+        : _mIndex(param->index()),
+          _mFieldId((T*)((uintptr_t)offset - (uintptr_t)param)) {}
+
+    template<typename S, typename T>
+    inline static C2ParamField Make(S& param, T& offset) {
+        return C2ParamField(param.index(), (uintptr_t)&offset - (uintptr_t)&param, sizeof(T));
+    }
+
+    /**
+     * Create a field identifier using a configuration parameter (variable),
+     * and a member pointer. This method cannot be used to refer to an
+     * array element or a subfield.
+     *
+     * ~~~~~~~~~~~~~ (.cpp)
+     *
+     * C2SomeParam mParam;
+     * C2ParamField(&mParam, &C2SomeParam::mMemberField);
+     *
+     * ~~~~~~~~~~~~~
+     *
+     * \param p pointer to parameter
+     * \param T member pointer to the field member
+     */
+    template<typename R, typename T, typename U>
+    inline C2ParamField(U *p, R T::* pm) : _mIndex(p->index()), _mFieldId(p, pm) { }
+
+    /**
+     * Create a field identifier to a configuration parameter (variable).
+     *
+     * ~~~~~~~~~~~~~ (.cpp)
+     *
+     * C2SomeParam mParam;
+     * C2ParamField(&mParam);
+     *
+     * ~~~~~~~~~~~~~
+     *
+     * \param param pointer to parameter
+     */
+    template<typename S>
+    inline C2ParamField(S* param)
+        : _mIndex(param->index()), _mFieldId(0u, param->size()) { }
+
+    /** Copy constructor. */
+    inline C2ParamField(const C2ParamField &other) = default;
+
+    /**
+     * Equality operator.
+     */
+    inline bool operator==(const C2ParamField &other) const {
+        return _mIndex == other._mIndex && _mFieldId == other._mFieldId;
+    }
+
+    /**
+     * Ordering operator.
+     */
+    inline bool operator<(const C2ParamField &other) const {
+        return _mIndex < other._mIndex ||
+            (_mIndex == other._mIndex && _mFieldId < other._mFieldId);
+    }
+
+    DEFINE_OTHER_COMPARISON_OPERATORS(C2ParamField)
+
+protected:
+    inline C2ParamField(C2Param::Index index, uint32_t offset, uint32_t size)
+        : _mIndex(index), _mFieldId(offset, size) {}
+
+private:
+    friend struct _C2ParamInspector;
+
+    C2Param::Index _mIndex; ///< parameter index
+    _C2FieldId _mFieldId;   ///< field identifier
+};
+
+/**
+ * A shared (union) representation of numeric values
+ */
+class C2Value {
+public:
+    /// A union of supported primitive types.
+    union Primitive {
+        // first member is always zero initialized so it must be the largest
+        uint64_t    u64;   ///< uint64_t value
+        int64_t     i64;   ///< int64_t value
+        c2_cntr64_t c64;   ///< c2_cntr64_t value
+        uint32_t    u32;   ///< uint32_t value
+        int32_t     i32;   ///< int32_t value
+        c2_cntr32_t c32;   ///< c2_cntr32_t value
+        float       fp;    ///< float value
+
+        // constructors - implicit
+        Primitive(uint64_t value)    : u64(value) { }
+        Primitive(int64_t value)     : i64(value) { }
+        Primitive(c2_cntr64_t value) : c64(value) { }
+        Primitive(uint32_t value)    : u32(value) { }
+        Primitive(int32_t value)     : i32(value) { }
+        Primitive(c2_cntr32_t value) : c32(value) { }
+        Primitive(uint8_t value)     : u32(value) { }
+        Primitive(char value)        : i32(value) { }
+        Primitive(float value)       : fp(value)  { }
+
+        // allow construction from enum type
+        template<typename E, typename = typename std::enable_if<std::is_enum<E>::value>::type>
+        Primitive(E value)
+            : Primitive(static_cast<typename std::underlying_type<E>::type>(value)) { }
+
+        Primitive() : u64(0) { }
+
+        /** gets value out of the union */
+        template<typename T> const T &ref() const;
+
+        // verify that we can assume standard aliasing
+        static_assert(sizeof(u64) == sizeof(i64), "");
+        static_assert(sizeof(u64) == sizeof(c64), "");
+        static_assert(sizeof(u32) == sizeof(i32), "");
+        static_assert(sizeof(u32) == sizeof(c32), "");
+    };
+    // verify that we can assume standard aliasing
+    static_assert(offsetof(Primitive, u64) == offsetof(Primitive, i64), "");
+    static_assert(offsetof(Primitive, u64) == offsetof(Primitive, c64), "");
+    static_assert(offsetof(Primitive, u32) == offsetof(Primitive, i32), "");
+    static_assert(offsetof(Primitive, u32) == offsetof(Primitive, c32), "");
+
+    enum type_t : uint32_t {
+        NO_INIT,
+        INT32,
+        UINT32,
+        CNTR32,
+        INT64,
+        UINT64,
+        CNTR64,
+        FLOAT,
+    };
+
+    template<typename T, bool = std::is_enum<T>::value>
+    inline static constexpr type_t TypeFor() {
+        using U = typename std::underlying_type<T>::type;
+        return TypeFor<U>();
+    }
+
+    // deprectated
+    template<typename T, bool B = std::is_enum<T>::value>
+    inline static constexpr type_t typeFor() {
+        return TypeFor<T, B>();
+    }
+
+    // constructors - implicit
+    template<typename T>
+    C2Value(T value)  : _mType(typeFor<T>()), _mValue(value) { }
+
+    C2Value() : _mType(NO_INIT) { }
+
+    inline type_t type() const { return _mType; }
+
+    template<typename T>
+    inline bool get(T *value) const {
+        if (_mType == typeFor<T>()) {
+            *value = _mValue.ref<T>();
+            return true;
+        }
+        return false;
+    }
+
+    /// returns the address of the value
+    void *get() const {
+        return _mType == NO_INIT ? nullptr : (void*)&_mValue;
+    }
+
+    /// returns the size of the contained value
+    size_t inline sizeOf() const {
+        return SizeFor(_mType);
+    }
+
+    static size_t SizeFor(type_t type) {
+        switch (type) {
+            case INT32:
+            case UINT32:
+            case CNTR32: return sizeof(_mValue.i32);
+            case INT64:
+            case UINT64:
+            case CNTR64: return sizeof(_mValue.i64);
+            case FLOAT: return sizeof(_mValue.fp);
+            default: return 0;
+        }
+    }
+
+private:
+    type_t _mType;
+    Primitive _mValue;
+};
+
+template<> inline const int32_t &C2Value::Primitive::ref<int32_t>() const { return i32; }
+template<> inline const int64_t &C2Value::Primitive::ref<int64_t>() const { return i64; }
+template<> inline const uint32_t &C2Value::Primitive::ref<uint32_t>() const { return u32; }
+template<> inline const uint64_t &C2Value::Primitive::ref<uint64_t>() const { return u64; }
+template<> inline const c2_cntr32_t &C2Value::Primitive::ref<c2_cntr32_t>() const { return c32; }
+template<> inline const c2_cntr64_t &C2Value::Primitive::ref<c2_cntr64_t>() const { return c64; }
+template<> inline const float &C2Value::Primitive::ref<float>() const { return fp; }
+
+// provide types for enums and uint8_t, char even though we don't provide reading as them
+template<> constexpr C2Value::type_t C2Value::TypeFor<char, false>() { return INT32; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<int32_t, false>() { return INT32; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<int64_t, false>() { return INT64; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<uint8_t, false>() { return UINT32; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<uint32_t, false>() { return UINT32; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<uint64_t, false>() { return UINT64; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<c2_cntr32_t, false>() { return CNTR32; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<c2_cntr64_t, false>() { return CNTR64; }
+template<> constexpr C2Value::type_t C2Value::TypeFor<float, false>() { return FLOAT; }
+
+// forward declare easy enum template
+template<typename E> struct C2EasyEnum;
+
+/**
+ * field descriptor. A field is uniquely defined by an index into a parameter.
+ * (Note: Stream-id is not captured as a field.)
+ *
+ * Ordering of fields is by offset. In case of structures, it is depth first,
+ * with a structure taking an index just before and in addition to its members.
+ */
+struct C2FieldDescriptor {
+//public:
+    /** field types and flags
+     * \note: only 32-bit and 64-bit fields are supported (e.g. no boolean, as that
+     * is represented using INT32).
+     */
+    enum type_t : uint32_t {
+        // primitive types
+        INT32   = C2Value::INT32,  ///< 32-bit signed integer
+        UINT32  = C2Value::UINT32, ///< 32-bit unsigned integer
+        CNTR32  = C2Value::CNTR32, ///< 32-bit counter
+        INT64   = C2Value::INT64,  ///< 64-bit signed integer
+        UINT64  = C2Value::UINT64, ///< 64-bit signed integer
+        CNTR64  = C2Value::CNTR64, ///< 64-bit counter
+        FLOAT   = C2Value::FLOAT,  ///< 32-bit floating point
+
+        // array types
+        STRING = 0x100, ///< fixed-size string (POD)
+        BLOB,           ///< blob. Blobs have no sub-elements and can be thought of as byte arrays;
+                        ///< however, bytes cannot be individually addressed by clients.
+
+        // complex types
+        STRUCT_FLAG = 0x20000, ///< structs. Marked with this flag in addition to their coreIndex.
+    };
+
+    typedef std::pair<C2String, C2Value::Primitive> NamedValueType;
+    typedef std::vector<NamedValueType> NamedValuesType;
+    //typedef std::pair<std::vector<C2String>, std::vector<C2Value::Primitive>> NamedValuesType;
+
+    /**
+     * Template specialization that returns the named values for a type.
+     *
+     * \todo hide from client.
+     *
+     * \return a vector of name-value pairs.
+     */
+    template<typename B>
+    static NamedValuesType namedValuesFor(const B &);
+
+    /** specialization for easy enums */
+    template<typename E>
+    inline static NamedValuesType namedValuesFor(const C2EasyEnum<E> &) {
+        return namedValuesFor(*(E*)nullptr);
+    }
+
+private:
+    template<typename B, bool enabled=std::is_arithmetic<B>::value || std::is_enum<B>::value>
+    struct C2_HIDE _NamedValuesGetter;
+
+public:
+    inline C2FieldDescriptor(uint32_t type, uint32_t extent, C2String name, size_t offset, size_t size)
+        : _mType((type_t)type), _mExtent(extent), _mName(name), _mFieldId(offset, size) { }
+
+    inline C2FieldDescriptor(const C2FieldDescriptor &) = default;
+
+    template<typename T, class B=typename std::remove_extent<T>::type>
+    inline C2FieldDescriptor(const T* offset, const char *name)
+        : _mType(this->GetType((B*)nullptr)),
+          _mExtent(std::is_array<T>::value ? std::extent<T>::value : 1),
+          _mName(name),
+          _mNamedValues(_NamedValuesGetter<B>::getNamedValues()),
+          _mFieldId(offset) {}
+
+/*
+    template<typename T, typename B=typename std::remove_extent<T>::type>
+    inline C2FieldDescriptor<T, B, false>(T* offset, const char *name)
+        : _mType(this->GetType((B*)nullptr)),
+          _mExtent(std::is_array<T>::value ? std::extent<T>::value : 1),
+          _mName(name),
+          _mFieldId(offset) {}
+*/
+
+    /// \deprecated
+    template<typename T, typename S, class B=typename std::remove_extent<T>::type>
+    inline C2FieldDescriptor(S*, T S::* field, const char *name)
+        : _mType(this->GetType((B*)nullptr)),
+          _mExtent(std::is_array<T>::value ? std::extent<T>::value : 1),
+          _mName(name),
+          _mFieldId(&(((S*)0)->*field)) {}
+
+    /// returns the type of this field
+    inline type_t type() const { return _mType; }
+    /// returns the length of the field in case it is an array. Returns 0 for
+    /// T[] arrays, returns 1 for T[1] arrays as well as if the field is not an array.
+    inline size_t extent() const { return _mExtent; }
+    /// returns the name of the field
+    inline C2String name() const { return _mName; }
+
+    const NamedValuesType &namedValues() const { return _mNamedValues; }
+
+#if defined(FRIEND_TEST)
+    friend void PrintTo(const C2FieldDescriptor &, ::std::ostream*);
+    friend bool operator==(const C2FieldDescriptor &, const C2FieldDescriptor &);
+    FRIEND_TEST(C2ParamTest_ParamFieldList, VerifyStruct);
+#endif
+
+private:
+    /**
+     * Construct an offseted field descriptor.
+     */
+    inline C2FieldDescriptor(const C2FieldDescriptor &desc, size_t offset)
+        : _mType(desc._mType), _mExtent(desc._mExtent),
+          _mName(desc._mName), _mNamedValues(desc._mNamedValues),
+          _mFieldId(desc._mFieldId._mOffset + offset, desc._mFieldId._mSize) { }
+
+    type_t _mType;
+    uint32_t _mExtent; // the last member can be arbitrary length if it is T[] array,
+                       // extending to the end of the parameter (this is marked with
+                       // 0). T[0]-s are not fields.
+    C2String _mName;
+    NamedValuesType _mNamedValues;
+
+    _C2FieldId _mFieldId;   // field identifier (offset and size)
+
+    // NOTE: We do not capture default value(s) here as that may depend on the component.
+    // NOTE: We also do not capture bestEffort, as 1) this should be true for most fields,
+    // 2) this is at parameter granularity.
+
+    // type resolution
+    inline static type_t GetType(int32_t*)     { return INT32; }
+    inline static type_t GetType(uint32_t*)    { return UINT32; }
+    inline static type_t GetType(c2_cntr32_t*) { return CNTR32; }
+    inline static type_t GetType(int64_t*)     { return INT64; }
+    inline static type_t GetType(uint64_t*)    { return UINT64; }
+    inline static type_t GetType(c2_cntr64_t*) { return CNTR64; }
+    inline static type_t GetType(float*)       { return FLOAT; }
+    inline static type_t GetType(char*)        { return STRING; }
+    inline static type_t GetType(uint8_t*)     { return BLOB; }
+
+    template<typename T,
+             class=typename std::enable_if<std::is_enum<T>::value>::type>
+    inline static type_t GetType(T*) {
+        typename std::underlying_type<T>::type underlying(0);
+        return GetType(&underlying);
+    }
+
+    // verify C2Struct by having a FieldList() and a CORE_INDEX.
+    template<typename T,
+             class=decltype(T::CORE_INDEX + 1), class=decltype(T::FieldList())>
+    inline static type_t GetType(T*) {
+        static_assert(!std::is_base_of<C2Param, T>::value, "cannot use C2Params as fields");
+        return (type_t)(T::CORE_INDEX | STRUCT_FLAG);
+    }
+
+    friend struct _C2ParamInspector;
+};
+
+// no named values for compound types
+template<typename B>
+struct C2FieldDescriptor::_NamedValuesGetter<B, false> {
+    inline static C2FieldDescriptor::NamedValuesType getNamedValues() {
+        return NamedValuesType();
+    }
+};
+
+template<typename B>
+struct C2FieldDescriptor::_NamedValuesGetter<B, true> {
+    inline static C2FieldDescriptor::NamedValuesType getNamedValues() {
+        return C2FieldDescriptor::namedValuesFor(*(B*)nullptr);
+    }
+};
+
+#define DEFINE_NO_NAMED_VALUES_FOR(type) \
+template<> inline C2FieldDescriptor::NamedValuesType C2FieldDescriptor::namedValuesFor(const type &) { \
+    return NamedValuesType(); \
+}
+
+// We cannot subtype constructor for enumerated types so insted define no named values for
+// non-enumerated integral types.
+DEFINE_NO_NAMED_VALUES_FOR(int32_t)
+DEFINE_NO_NAMED_VALUES_FOR(uint32_t)
+DEFINE_NO_NAMED_VALUES_FOR(c2_cntr32_t)
+DEFINE_NO_NAMED_VALUES_FOR(int64_t)
+DEFINE_NO_NAMED_VALUES_FOR(uint64_t)
+DEFINE_NO_NAMED_VALUES_FOR(c2_cntr64_t)
+DEFINE_NO_NAMED_VALUES_FOR(uint8_t)
+DEFINE_NO_NAMED_VALUES_FOR(char)
+DEFINE_NO_NAMED_VALUES_FOR(float)
+
+/**
+ * Describes the fields of a structure.
+ */
+struct C2StructDescriptor {
+public:
+    /// Returns the core index of the struct
+    inline C2Param::CoreIndex coreIndex() const { return _mType.coreIndex(); }
+
+    // Returns the number of fields in this struct (not counting any recursive fields).
+    // Must be at least 1 for valid structs.
+    inline size_t numFields() const { return _mFields.size(); }
+
+    // Returns the list of direct fields (not counting any recursive fields).
+    typedef std::vector<C2FieldDescriptor>::const_iterator field_iterator;
+    inline field_iterator cbegin() const { return _mFields.cbegin(); }
+    inline field_iterator cend() const { return _mFields.cend(); }
+
+    // only supplying const iterator - but these names are needed for range based loops
+    inline field_iterator begin() const { return _mFields.cbegin(); }
+    inline field_iterator end() const { return _mFields.cend(); }
+
+    template<typename T>
+    inline C2StructDescriptor(T*)
+        : C2StructDescriptor(T::CORE_INDEX, T::FieldList()) { }
+
+    inline C2StructDescriptor(
+            C2Param::CoreIndex type,
+            const std::vector<C2FieldDescriptor> &fields)
+        : _mType(type), _mFields(fields) { }
+
+private:
+    friend struct _C2ParamInspector;
+
+    inline C2StructDescriptor(
+            C2Param::CoreIndex type,
+            std::vector<C2FieldDescriptor> &&fields)
+        : _mType(type), _mFields(std::move(fields)) { }
+
+    const C2Param::CoreIndex _mType;
+    const std::vector<C2FieldDescriptor> _mFields;
+};
+
+/**
+ * Describes parameters for a component.
+ */
+struct C2ParamDescriptor {
+public:
+    /**
+     * Returns whether setting this param is required to configure this component.
+     * This can only be true for builtin params for platform-defined components (e.g. video and
+     * audio encoders/decoders, video/audio filters).
+     * For vendor-defined components, it can be true even for vendor-defined params,
+     * but it is not recommended, in case the component becomes platform-defined.
+     */
+    inline bool isRequired() const { return _mAttrib & IS_REQUIRED; }
+
+    /**
+     * Returns whether this parameter is persistent. This is always true for C2Tuning and C2Setting,
+     * but may be false for C2Info. If true, this parameter persists across frames and applies to
+     * the current and subsequent frames. If false, this C2Info parameter only applies to the
+     * current frame and is not assumed to have the same value (or even be present) on subsequent
+     * frames, unless it is specified for those frames.
+     */
+    inline bool isPersistent() const { return _mAttrib & IS_PERSISTENT; }
+
+    inline bool isStrict() const { return _mAttrib & IS_STRICT; }
+
+    inline bool isReadOnly() const { return _mAttrib & IS_READ_ONLY; }
+
+    inline bool isVisible() const { return !(_mAttrib & IS_HIDDEN); }
+
+    inline bool isPublic() const { return !(_mAttrib & IS_INTERNAL); }
+
+    /// Returns the name of this param.
+    /// This defaults to the underlying C2Struct's name, but could be altered for a component.
+    inline C2String name() const { return _mName; }
+
+    /// Returns the parameter index
+    inline C2Param::Index index() const { return _mIndex; }
+
+    /// Returns the indices of parameters that this parameter has a dependency on
+    inline const std::vector<C2Param::Index> &dependencies() const { return _mDependencies; }
+
+    /// \deprecated
+    template<typename T>
+    inline C2ParamDescriptor(bool isRequired, C2StringLiteral name, const T*)
+        : _mIndex(T::PARAM_TYPE),
+          _mAttrib(IS_PERSISTENT | (isRequired ? IS_REQUIRED : 0)),
+          _mName(name) { }
+
+    /// \deprecated
+    inline C2ParamDescriptor(
+            bool isRequired, C2StringLiteral name, C2Param::Index index)
+        : _mIndex(index),
+          _mAttrib(IS_PERSISTENT | (isRequired ? IS_REQUIRED : 0)),
+          _mName(name) { }
+
+    enum attrib_t : uint32_t {
+        // flags that default on
+        IS_REQUIRED   = 1u << 0, ///< parameter is required to be specified
+        IS_PERSISTENT = 1u << 1, ///< parameter retains its value
+        // flags that default off
+        IS_STRICT     = 1u << 2, ///< parameter is strict
+        IS_READ_ONLY  = 1u << 3, ///< parameter is publicly read-only
+        IS_HIDDEN     = 1u << 4, ///< parameter shall not be visible to clients
+        IS_INTERNAL   = 1u << 5, ///< parameter shall not be used by framework (other than testing)
+        IS_CONST      = 1u << 6 | IS_READ_ONLY, ///< parameter is publicly const (hence read-only)
+    };
+
+    inline C2ParamDescriptor(
+        C2Param::Index index, attrib_t attrib, C2StringLiteral name)
+        : _mIndex(index),
+          _mAttrib(attrib),
+          _mName(name) { }
+
+    inline C2ParamDescriptor(
+        C2Param::Index index, attrib_t attrib, C2String &&name,
+        std::vector<C2Param::Index> &&dependencies)
+        : _mIndex(index),
+          _mAttrib(attrib),
+          _mName(name),
+          _mDependencies(std::move(dependencies)) { }
+
+private:
+    const C2Param::Index _mIndex;
+    const uint32_t _mAttrib;
+    const C2String _mName;
+    std::vector<C2Param::Index> _mDependencies;
+
+    friend struct _C2ParamInspector;
+};
+
+DEFINE_ENUM_OPERATORS(::C2ParamDescriptor::attrib_t)
+
+
+/// \ingroup internal
+/// Define a structure without CORE_INDEX.
+/// \note _FIELD_LIST is used only during declaration so that C2Struct declarations can end with
+/// a simple list of C2FIELD-s and closing bracket. Mark it unused as it is not used in templated
+/// structs.
+#define DEFINE_BASE_C2STRUCT(name) \
+private: \
+    const static std::vector<C2FieldDescriptor> _FIELD_LIST __unused; /**< structure fields */ \
+public: \
+    typedef C2##name##Struct _type; /**< type name shorthand */ \
+    static const std::vector<C2FieldDescriptor> FieldList(); /**< structure fields factory */
+
+/// Define a structure with matching CORE_INDEX.
+#define DEFINE_C2STRUCT(name) \
+public: \
+    enum : uint32_t { CORE_INDEX = kParamIndex##name }; \
+    DEFINE_BASE_C2STRUCT(name)
+
+/// Define a flexible structure without CORE_INDEX.
+#define DEFINE_BASE_FLEX_C2STRUCT(name, flexMember) \
+public: \
+    FLEX(C2##name##Struct, flexMember) \
+    DEFINE_BASE_C2STRUCT(name)
+
+/// Define a flexible structure with matching CORE_INDEX.
+#define DEFINE_FLEX_C2STRUCT(name, flexMember) \
+public: \
+    FLEX(C2##name##Struct, flexMember) \
+    enum : uint32_t { CORE_INDEX = kParamIndex##name | C2Param::CoreIndex::IS_FLEX_FLAG }; \
+    DEFINE_BASE_C2STRUCT(name)
+
+/// \ingroup internal
+/// Describe a structure of a templated structure.
+// Use list... as the argument gets resubsitituted and it contains commas. Alternative would be
+// to wrap list in an expression, e.g. ({ std::vector<C2FieldDescriptor> list; })) which converts
+// it from an initializer list to a vector.
+#define DESCRIBE_TEMPLATED_C2STRUCT(strukt, list...) \
+    _DESCRIBE_TEMPLATABLE_C2STRUCT(template<>, strukt, __C2_GENERATE_GLOBAL_VARS__, list)
+
+/// \deprecated
+/// Describe the fields of a structure using an initializer list.
+#define DESCRIBE_C2STRUCT(name, list...) \
+    _DESCRIBE_TEMPLATABLE_C2STRUCT(, C2##name##Struct, __C2_GENERATE_GLOBAL_VARS__, list)
+
+/// \ingroup internal
+/// Macro layer to get value of enabled that is passed in as a macro variable
+#define _DESCRIBE_TEMPLATABLE_C2STRUCT(template, strukt, enabled, list...) \
+    __DESCRIBE_TEMPLATABLE_C2STRUCT(template, strukt, enabled, list)
+
+/// \ingroup internal
+/// Macro layer to resolve to the specific macro based on macro variable
+#define __DESCRIBE_TEMPLATABLE_C2STRUCT(template, strukt, enabled, list...) \
+    ___DESCRIBE_TEMPLATABLE_C2STRUCT##enabled(template, strukt, list)
+
+#define ___DESCRIBE_TEMPLATABLE_C2STRUCT(template, strukt, list...) \
+    template \
+    const std::vector<C2FieldDescriptor> strukt::FieldList() { return list; }
+
+#define ___DESCRIBE_TEMPLATABLE_C2STRUCT__C2_GENERATE_GLOBAL_VARS__(template, strukt, list...)
+
+/**
+ * Describe a field of a structure.
+ * These must be in order.
+ *
+ * There are two ways to use this macro:
+ *
+ *  ~~~~~~~~~~~~~ (.cpp)
+ *  struct C2VideoWidthStruct {
+ *      int32_t width;
+ *      C2VideoWidthStruct() {} // optional default constructor
+ *      C2VideoWidthStruct(int32_t _width) : width(_width) {}
+ *
+ *      DEFINE_AND_DESCRIBE_C2STRUCT(VideoWidth)
+ *      C2FIELD(width, "width")
+ *  };
+ *  ~~~~~~~~~~~~~
+ *
+ *  ~~~~~~~~~~~~~ (.cpp)
+ *  struct C2VideoWidthStruct {
+ *      int32_t width;
+ *      C2VideoWidthStruct() = default; // optional default constructor
+ *      C2VideoWidthStruct(int32_t _width) : width(_width) {}
+ *
+ *      DEFINE_C2STRUCT(VideoWidth)
+ *  } C2_PACK;
+ *
+ *  DESCRIBE_C2STRUCT(VideoWidth, {
+ *      C2FIELD(width, "width")
+ *  })
+ *  ~~~~~~~~~~~~~
+ *
+ *  For flexible structures (those ending in T[]), use the flexible macros:
+ *
+ *  ~~~~~~~~~~~~~ (.cpp)
+ *  struct C2VideoFlexWidthsStruct {
+ *      int32_t widths[];
+ *      C2VideoFlexWidthsStruct(); // must have a default constructor
+ *
+ *  private:
+ *      // may have private constructors taking number of widths as the first argument
+ *      // This is used by the C2Param factory methods, e.g.
+ *      //   C2VideoFlexWidthsGlobalParam::AllocUnique(size_t, int32_t);
+ *      C2VideoFlexWidthsStruct(size_t flexCount, int32_t value) {
+ *          for (size_t i = 0; i < flexCount; ++i) {
+ *              widths[i] = value;
+ *          }
+ *      }
+ *
+ *      // If the last argument is T[N] or std::initializer_list<T>, the flexCount will
+ *      // be automatically calculated and passed by the C2Param factory methods, e.g.
+ *      //   int widths[] = { 1, 2, 3 };
+ *      //   C2VideoFlexWidthsGlobalParam::AllocUnique(widths);
+ *      template<unsigned N>
+ *      C2VideoFlexWidthsStruct(size_t flexCount, const int32_t(&init)[N]) {
+ *          for (size_t i = 0; i < flexCount; ++i) {
+ *              widths[i] = init[i];
+ *          }
+ *      }
+ *
+ *      DEFINE_AND_DESCRIBE_FLEX_C2STRUCT(VideoFlexWidths, widths)
+ *      C2FIELD(widths, "widths")
+ *  };
+ *  ~~~~~~~~~~~~~
+ *
+ *  ~~~~~~~~~~~~~ (.cpp)
+ *  struct C2VideoFlexWidthsStruct {
+ *      int32_t mWidths[];
+ *      C2VideoFlexWidthsStruct(); // must have a default constructor
+ *
+ *      DEFINE_FLEX_C2STRUCT(VideoFlexWidths, mWidths)
+ *  } C2_PACK;
+ *
+ *  DESCRIBE_C2STRUCT(VideoFlexWidths, {
+ *      C2FIELD(mWidths, "widths")
+ *  })
+ *  ~~~~~~~~~~~~~
+ *
+ */
+#define DESCRIBE_C2FIELD(member, name) \
+  C2FieldDescriptor(&((_type*)(nullptr))->member, name),
+
+#define C2FIELD(member, name) _C2FIELD(member, name, __C2_GENERATE_GLOBAL_VARS__)
+/// \if 0
+#define _C2FIELD(member, name, enabled) __C2FIELD(member, name, enabled)
+#define __C2FIELD(member, name, enabled) DESCRIBE_C2FIELD##enabled(member, name)
+#define DESCRIBE_C2FIELD__C2_GENERATE_GLOBAL_VARS__(member, name)
+/// \endif
+
+/// Define a structure with matching CORE_INDEX and start describing its fields.
+/// This must be at the end of the structure definition.
+#define DEFINE_AND_DESCRIBE_C2STRUCT(name) \
+    _DEFINE_AND_DESCRIBE_C2STRUCT(name, DEFINE_C2STRUCT, __C2_GENERATE_GLOBAL_VARS__)
+
+/// Define a base structure (with no CORE_INDEX) and start describing its fields.
+/// This must be at the end of the structure definition.
+#define DEFINE_AND_DESCRIBE_BASE_C2STRUCT(name) \
+    _DEFINE_AND_DESCRIBE_C2STRUCT(name, DEFINE_BASE_C2STRUCT, __C2_GENERATE_GLOBAL_VARS__)
+
+/// Define a flexible structure with matching CORE_INDEX and start describing its fields.
+/// This must be at the end of the structure definition.
+#define DEFINE_AND_DESCRIBE_FLEX_C2STRUCT(name, flexMember) \
+    _DEFINE_AND_DESCRIBE_FLEX_C2STRUCT( \
+            name, flexMember, DEFINE_FLEX_C2STRUCT, __C2_GENERATE_GLOBAL_VARS__)
+
+/// Define a flexible base structure (with no CORE_INDEX) and start describing its fields.
+/// This must be at the end of the structure definition.
+#define DEFINE_AND_DESCRIBE_BASE_FLEX_C2STRUCT(name, flexMember) \
+    _DEFINE_AND_DESCRIBE_FLEX_C2STRUCT( \
+            name, flexMember, DEFINE_BASE_FLEX_C2STRUCT, __C2_GENERATE_GLOBAL_VARS__)
+
+/// \if 0
+/*
+   Alternate declaration of field definitions in case no field list is to be generated.
+   The specific macro is chosed based on the value of __C2_GENERATE_GLOBAL_VARS__ (whether it is
+   defined (to be empty) or not. This requires two level of macro substitution.
+   TRICKY: use namespace declaration to handle closing bracket that is normally after
+   these macros.
+*/
+
+#define _DEFINE_AND_DESCRIBE_C2STRUCT(name, defineMacro, enabled) \
+    __DEFINE_AND_DESCRIBE_C2STRUCT(name, defineMacro, enabled)
+#define __DEFINE_AND_DESCRIBE_C2STRUCT(name, defineMacro, enabled) \
+    ___DEFINE_AND_DESCRIBE_C2STRUCT##enabled(name, defineMacro)
+#define ___DEFINE_AND_DESCRIBE_C2STRUCT__C2_GENERATE_GLOBAL_VARS__(name, defineMacro) \
+    defineMacro(name) } C2_PACK; namespace {
+#define ___DEFINE_AND_DESCRIBE_C2STRUCT(name, defineMacro) \
+    defineMacro(name) } C2_PACK; \
+    const std::vector<C2FieldDescriptor> C2##name##Struct::FieldList() { return _FIELD_LIST; } \
+    const std::vector<C2FieldDescriptor> C2##name##Struct::_FIELD_LIST = {
+
+#define _DEFINE_AND_DESCRIBE_FLEX_C2STRUCT(name, flexMember, defineMacro, enabled) \
+    __DEFINE_AND_DESCRIBE_FLEX_C2STRUCT(name, flexMember, defineMacro, enabled)
+#define __DEFINE_AND_DESCRIBE_FLEX_C2STRUCT(name, flexMember, defineMacro, enabled) \
+    ___DEFINE_AND_DESCRIBE_FLEX_C2STRUCT##enabled(name, flexMember, defineMacro)
+#define ___DEFINE_AND_DESCRIBE_FLEX_C2STRUCT__C2_GENERATE_GLOBAL_VARS__(name, flexMember, defineMacro) \
+    defineMacro(name, flexMember) } C2_PACK; namespace {
+#define ___DEFINE_AND_DESCRIBE_FLEX_C2STRUCT(name, flexMember, defineMacro) \
+    defineMacro(name, flexMember) } C2_PACK; \
+    const std::vector<C2FieldDescriptor> C2##name##Struct::FieldList() { return _FIELD_LIST; } \
+    const std::vector<C2FieldDescriptor> C2##name##Struct::_FIELD_LIST = {
+/// \endif
+
+
+/**
+ * Parameter reflector class.
+ *
+ * This class centralizes the description of parameter structures. This can be shared
+ * by multiple components as describing a parameter does not imply support of that
+ * parameter. However, each supported parameter and any dependent structures within
+ * must be described by the parameter reflector provided by a component.
+ */
+class C2ParamReflector {
+public:
+    /**
+     *  Describes a parameter structure.
+     *
+     *  \param[in] coreIndex the core index of the parameter structure containing at least the
+     *  core index
+     *
+     *  \return the description of the parameter structure
+     *  \retval nullptr if the parameter is not supported by this reflector
+     *
+     *  This methods shall not block and return immediately.
+     *
+     *  \note this class does not take a set of indices because we would then prefer
+     *  to also return any dependent structures, and we don't want this logic to be
+     *  repeated in each reflector. Alternately, this could just return a map of all
+     *  descriptions, but we want to conserve memory if client only wants the description
+     *  of a few indices.
+     */
+    virtual std::unique_ptr<C2StructDescriptor> describe(C2Param::CoreIndex coreIndex) const = 0;
+
+protected:
+    virtual ~C2ParamReflector() = default;
+};
+
+/**
+ * Generic supported values for a field.
+ *
+ * This can be either a range or a set of values. The range can be a simple range, an arithmetic,
+ * geometric or multiply-accumulate series with a clear minimum and maximum value. Values can
+ * be discrete values, or can optionally represent flags to be or-ed.
+ *
+ * \note Do not use flags to represent bitfields. Use individual values or separate fields instead.
+ */
+struct C2FieldSupportedValues {
+//public:
+    enum type_t {
+        EMPTY,      ///< no supported values
+        RANGE,      ///< a numeric range that can be continuous or discrete
+        VALUES,     ///< a list of values
+        FLAGS       ///< a list of flags that can be OR-ed
+    };
+
+    type_t type; /** Type of values for this field. */
+
+    typedef C2Value::Primitive Primitive;
+
+    /**
+     * Range specifier for supported value. Used if type is RANGE.
+     *
+     * If step is 0 and num and denom are both 1, the supported values are any value, for which
+     * min <= value <= max.
+     *
+     * Otherwise, the range represents a geometric/arithmetic/multiply-accumulate series, where
+     * successive supported values can be derived from previous values (starting at min), using the
+     * following formula:
+     *  v[0] = min
+     *  v[i] = v[i-1] * num / denom + step for i >= 1, while min < v[i] <= max.
+     */
+    struct {
+        /** Lower end of the range (inclusive). */
+        Primitive min;
+        /** Upper end of the range (inclusive if permitted by series). */
+        Primitive max;
+        /** Step between supported values. */
+        Primitive step;
+        /** Numerator of a geometric series. */
+        Primitive num;
+        /** Denominator of a geometric series. */
+        Primitive denom;
+    } range;
+
+    /**
+     * List of values. Used if type is VALUES or FLAGS.
+     *
+     * If type is VALUES, this is the list of supported values in decreasing preference.
+     *
+     * If type is FLAGS, this vector contains { min-mask, flag1, flag2... }. Basically, the first
+     * value is the required set of flags to be set, and the rest of the values are flags that can
+     * be set independently. FLAGS is only supported for integral types. Supported flags should
+     * not overlap, as it can make validation non-deterministic. The standard validation method
+     * is that starting from the original value, if each flag is removed when fully present (the
+     * min-mask must be fully present), we shall arrive at 0.
+     */
+    std::vector<Primitive> values;
+
+    C2FieldSupportedValues()
+        : type(EMPTY) {
+    }
+
+    template<typename T>
+    C2FieldSupportedValues(T min, T max, T step = T(std::is_floating_point<T>::value ? 0 : 1))
+        : type(RANGE),
+          range{min, max, step, (T)1, (T)1} { }
+
+    template<typename T>
+    C2FieldSupportedValues(T min, T max, T num, T den) :
+        type(RANGE),
+        range{min, max, (T)0, num, den} { }
+
+    template<typename T>
+    C2FieldSupportedValues(T min, T max, T step, T num, T den)
+        : type(RANGE),
+          range{min, max, step, num, den} { }
+
+    /// \deprecated
+    template<typename T>
+    C2FieldSupportedValues(bool flags, std::initializer_list<T> list)
+        : type(flags ? FLAGS : VALUES),
+          range{(T)0, (T)0, (T)0, (T)0, (T)0} {
+        for (T value : list) {
+            values.emplace_back(value);
+        }
+    }
+
+    /// \deprecated
+    template<typename T>
+    C2FieldSupportedValues(bool flags, const std::vector<T>& list)
+        : type(flags ? FLAGS : VALUES),
+          range{(T)0, (T)0, (T)0, (T)0, (T)0} {
+        for(T value : list) {
+            values.emplace_back(value);
+        }
+    }
+
+    /// \internal
+    /// \todo: create separate values vs. flags initializer as for flags we want
+    /// to list both allowed and required flags
+    template<typename T, typename E=decltype(C2FieldDescriptor::namedValuesFor(*(T*)0))>
+    C2FieldSupportedValues(bool flags, const T*)
+        : type(flags ? FLAGS : VALUES),
+          range{(T)0, (T)0, (T)0, (T)0, (T)0} {
+              C2FieldDescriptor::NamedValuesType named = C2FieldDescriptor::namedValuesFor(*(T*)0);
+        if (flags) {
+            values.emplace_back(0); // min-mask defaults to 0
+        }
+        for (const C2FieldDescriptor::NamedValueType &item : named){
+            values.emplace_back(item.second);
+        }
+    }
+};
+
+/**
+ * Supported values for a specific field.
+ *
+ * This is a pair of the field specifier together with an optional supported values object.
+ * This structure is used when reporting parameter configuration failures and conflicts.
+ */
+struct C2ParamFieldValues {
+    C2ParamField paramOrField; ///< the field or parameter
+    /// optional supported values for the field if paramOrField specifies an actual field that is
+    /// numeric (non struct, blob or string). Supported values for arrays (including string and
+    /// blobs) describe the supported values for each element (character for string, and bytes for
+    /// blobs). It is optional for read-only strings and blobs.
+    std::unique_ptr<C2FieldSupportedValues> values;
+
+    // This struct is meant to be move constructed.
+    C2_DEFAULT_MOVE(C2ParamFieldValues);
+
+    // Copy constructor/assignment is also provided as this object may get copied.
+    C2ParamFieldValues(const C2ParamFieldValues &other)
+        : paramOrField(other.paramOrField),
+          values(other.values ? std::make_unique<C2FieldSupportedValues>(*other.values) : nullptr) { }
+
+    C2ParamFieldValues& operator=(const C2ParamFieldValues &other) {
+        paramOrField = other.paramOrField;
+        values = other.values ? std::make_unique<C2FieldSupportedValues>(*other.values) : nullptr;
+        return *this;
+    }
+
+
+    /**
+     * Construct with no values.
+     */
+    C2ParamFieldValues(const C2ParamField &paramOrField_)
+        : paramOrField(paramOrField_) { }
+
+    /**
+     * Construct with values.
+     */
+    C2ParamFieldValues(const C2ParamField &paramOrField_, const C2FieldSupportedValues &values_)
+        : paramOrField(paramOrField_),
+          values(std::make_unique<C2FieldSupportedValues>(values_)) { }
+
+    /**
+     * Construct from fields.
+     */
+    C2ParamFieldValues(const C2ParamField &paramOrField_, std::unique_ptr<C2FieldSupportedValues> &&values_)
+        : paramOrField(paramOrField_),
+          values(std::move(values_)) { }
+};
+
+/// @}
+
+// include debug header for C2Params.h if C2Debug.h was already included
+#ifdef C2UTILS_DEBUG_H_
+#include <util/C2Debug-param.h>
+#endif
+
+#endif  // C2PARAM_H_